On a balance sheet, QuickBooks automatically rolls earnings from all prior years to the special Retained Earnings account it creates when the company file is created.
If someone renamed that special account and created another equity account called "Retained Earnings", that could cause what you're seeing.
You can check to see if this is the case because the special retained earnings Equity account, no matter what it is called, will not display a balance on your chart of accounts. It's the only Equity account that behaves that way.